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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '99ce9bd6cf6da665aedf994f8dfc5a670a51252d238e00cd89bef62d91427b4c' 
  AND token = 'KzljZFUf+xkaVyDLRjTvLSkzDcmdy41WoHPd6ancI0A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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