SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e1b4bacf850643c83e96e3e16efece1236f5ddcbcdeebc8357169f09ff5c3dbb' 
  AND token = 'xm4mgsIBjSwTADMWhWFtxTFn94H48VlbQkCW7W9jC30=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00020

JSON explain

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