SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c01984529196f8c3f6d9c507895f008f4c222e62eefb21e06d72b04acdc1f6c8' 
  AND token = 'pybCernDUVD5Yuna5pCAsUr6w2rxWlnirxITJdjegDs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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