SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '9b12e3b5bb711cd1703c469224a5550a9bb2aee1e792cebb92a58152da5afbe1' 
  AND token = '+gTubOFhUIBBdrnCQBWteDITHoeD+Ff83LQJK2sS6RA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00026

JSON explain

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