SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4f7ca445c73eaa2383b9dbbaa74aa9b55a5aba96e0085e3a3e8301ab121f86ce' 
  AND token = 'RCS0qO+DDYus3JiAgZQV1z/dqfMN9Fi+EdP6i4z3/cA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00007

JSON explain

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