SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c575b23523c9172f3de1397600af381690f5a734b34b923aaadc7ce18288449a' 
  AND token = 'aiiCwhOOSsOAilOUQPhcatvAbbqsoz7kA2fmt8NV0hg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00077

JSON explain

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