SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a0544f62454e3201ffbe4421d8d526613fffd68818d14b81dee3a9c83d0dd393' 
  AND token = 'fsf7oMAo8GL4lHk78nmwDZvibQ2C+biaaXUQeAqR4YQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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