SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6c1d3892effd25075c286e0b22129fbd8ac99e514d047932d6748d6a385457bf' 
  AND token = 'llbzA73idKKoT3DbmMvib3l1QKKn2radLLTCuYHIVbQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

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