SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a50d966adc5811db5d491260f8b1dc9d970e51b27af154c0d8aaf3beac5ed0e0' 
  AND token = 'PktQ8lDaW3IzlgpfsU4gNrNb92SwM2kW++ykX2e4e7A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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