SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '88606df789920b74005c83df3456f5dec06fead627565ada280376cea0e4e447' 
  AND token = 'R/fTIKsU5ZpODWLZGAW/gADswdfbYFBbHMMBjJXJhJA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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