SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '210ad11ff13b6c51bf5015b4a986e9615cba6f67b83d6f6c24395a74c6ea5471' 
  AND token = 'MldbzlNBqTKaHhjstKrg07mnnHrV3+p/unW4XbW/y0I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00058

JSON explain

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