SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd21c4ca8b4784a2077d08b460545ecaa1aa177fc7d3199d7356f524dd6a2983e' 
  AND token = 'z9x+J5IoSuSGkw4gVvAeOvGAfEBS3QrgOWhJQ9NLrdw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00092

JSON explain

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