SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b1a3bcd7a214c043553fba916035be03249d6932063ea936554403d0cc871e9e' 
  AND token = 'aiwmsWk923xCmDL/PeeCPIbz1vjeAp4phBPGndjNJnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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