SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '42b7a14d139a4cdd51d1e856f02a00208c68467b53cdb97ffb158bff60fff323' 
  AND token = '5NnPbIJ2geKTDBH5pz7bAI9fpUQJMeGXlvFdv8U3GYg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00396

JSON explain

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