SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f20c420400f3184692d102ab85b76a442553cf2b6e3a75cde3e4f17ce6023c6a' 
  AND token = 'j8URqNt3XRUg9zeM+mbakAlHY3aKBKDMjPs/CXXFTHU=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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