SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '991a352bc54f91ab3576585de8f4fb4e35065e9c4f540731844631b9a443c82b' 
  AND token = '5IyqLKBCR/Adg8tvSUzvBkX8Dy16Ao9yByXVHk1dJA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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