SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3a1340944720e4e9ea5b8d34d45260732c2e5fdc5af0114c27fb41886a21b682' 
  AND token = 'qvUnvejcZZcYEbzHBDLPdywOPgJe6g/pG75vOMj+LfU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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