SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '788aafed0fc543135889aa85f2f8f0c77c26cc05b0a72006e03922e595d12c0d' 
  AND token = 'OpooQwzdm2+e/oQHCacNKl/mGAdr6sUv9qLNLp0MfmY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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