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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6cead6fc47710cee1aa5a889c1d2de6ca6759afbf20a997dbba63371c66cec68' 
  AND token = 'u73X367uD8ObFDCPBzSvayTgM8l9ymcuVFnWt/fW53E=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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