SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3f5b0e9445f48e2e0a185f0b1c43dcce90b7412c1c177274f60762b753d69ae6' 
  AND token = 'WjUVIhrcDM+CEp12wVFh/jqlydIC3ILu4/BuZequiFo=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00034

JSON explain

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