SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a4c2009e24048e019cd7746d6e6de407a09b0040eb69bd250c7426632e0b959f' 
  AND token = 'kAViUxVE8+HWSKAPHpes0nURkl579glRWhq8KAkOqdQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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