SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5b996df4486c6c9828b2c86cb982385181b4c800a4dc9febbbe1da5afa61786f' 
  AND token = 'XOWMXSX3R4JBpiw+v1kDo/S3y7bAwEbcRzymROw7otk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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