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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '917c95c45287e0a0daee0e8b90b2f5097ce5848d1a75fa4d58bf9e95a7eb1b9a' 
  AND token = '9ejxsc+yFwj9w1xGQG7rWBrtDHHSe9lL8lnyYUMK/Ms=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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