SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '1e176c4603175fe82ad63292bc187b51a0c0988659631e925ab4510152608c57' 
  AND token = 'q0m4Ft0+Lcfn7Y7Bzv0wbBj5dwQLAhkUJ28+XAAE0Fc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00007

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}