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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6dcf101d02bb4bde6319889d9a0de07cc3fe0f6f2a9f7accd57d4082fe9d05ee' 
  AND token = 'fR/hVmhz9A96dUMc5tqoQoFbqspL2kGxQNRzo6PN/hA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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