SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'eac9fd617c6aa6363c7855594ef37b3cb543a1fbd7aab9eda03bdd1a523a0187' 
  AND token = '6nkkEaDXMXQOcMqK7xaejCu+zc4cRTxqOdRJzcgTWpw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00029

JSON explain

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