SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cfc3899b76de8d460a734caf7b17a070a3c91a1d17e2ee97278c7edff73352c1' 
  AND token = 'S5nELg8g8hKumsNXD1eZ7L6s+bALRLZ5GQ6UH+Npb0M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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