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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6e18ab2e1e8ef3eaa57f94271ad4ac26a2390699d9bd764d18d84b03eb8daefe' 
  AND token = 'sncKCUf3WtaRPlfEYcGD8hfhlVR8HEFZvvupRtkndQI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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