SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '2cb8f092f5ef7383ddc572a4ce3d486dee6ae9b1d83034b869d2e984b350e9a5' 
  AND token = 'bXcrXc5UHlSJDWhK3Cz5SDCXNnBfi7oCKkJ96d7urvo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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