SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb90de6a714bde416013c94f18c112158e0c34a976b10335b132778261d88873' 
  AND token = 'B2OUMiI8v65EDyHGu+/jnt3RCQaGwXqz3T5K513EygQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00030

JSON explain

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