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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6aa4e99015132c515ba22aa9d457b3fd4e713805370ed0f511e2ad9421ebd61' 
  AND token = 'QJ+9t4Rw8Z34pxaVxygkkALdx1pFpxZnm3XGGK2RSLA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

{
  "query_block": {
    "select_id": 1,
    "message": "no matching row in const table"
  }
}