SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a2ac20efe00d9d1459897d392991868feaf33abaaca990652c484a849c64fed3' 
  AND token = 'RBoUdDQF7wMMKyJt1Mc8W47HohYbiN3tnAv7KdmXyfA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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