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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f568b3cf6c396a2a09966fdca0e3ddd8e1c71e2d079184ea1ca19a2e1d59e889' 
  AND token = 'GK60F/fjv52h1ZX8Uj4xjefmeVzYUg7p7vMQKRU8Qq4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00017

JSON explain

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