SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f92554c6e6326d161813369df58e45eea51d05a19255b45648209e268014eb44' 
  AND token = 'zzwp06mYircGxDCsumxwUYE1OiaR/2kIFwkvNeIHXCM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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