SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'ba7edbfe79a83049425a0370bb5296786b3dca934324709f275981fe395f1e51' 
  AND token = 'lQKXL/sjczzl4yv5QC1+/+ZHoNmaHeMA8eFDGZkxyK8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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