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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d89d1b6a9d9b1baf4d723aec0f3bb37367868918247ee78a49efc29ed4bde91' 
  AND token = 'hzOCC2kpFVpSHHSNjWzPEnc7rVGs/jhyRYMpHe2oUH8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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