SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b8ee76a40bf8003c6b267e3600cf87da817d9a6729992cbdffc8d15f59bece44' 
  AND token = 'XQz1308GVpPX6VZpA6oZjnWTnSaMYeSBlJFQZ40gNPs=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}