SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21976471622500324b2fc08adcff60cf241683dc0775be404f18e4ccf714c465' 
  AND token = '3DcDy41kLtnsq0UPZVAf7BRrm79Gq8Pb20ZRA/4hs+w=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00053

JSON explain

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