SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '174732687454489b1bac9e90492fc8b8561217d3d5a369d3a16858f5d57663b1' 
  AND token = 'hPcp1HCePQuEYRdfMjH7SFuJLO7zfg7pZR3TjN9ZKBE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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