SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e37764d0ffc313398b37bbb0401da2a8f7635537c1fa41916651b9f6446ab100' 
  AND token = '7+baQdwLiksWquZKwcRdHV95VbogrmaR0gEJXdccX2Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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