SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '5710fec76b7df81fe8e22ebb26c9aaed75895ff908e0eec1ed3a141c037da13b' 
  AND token = 'BpRq/Im+O7nBT3TPiSjjWdSfA13k9U44Uoc9MmYyIyQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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