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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b377b8a540ec58cd877c2c7cd1258c467aac8f6d7c70f05556a3e4450a37f68' 
  AND token = 'QUDS67bWGn/tF8G1ai+VT7mlan/6zEwnlIt/GniLWIQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00043

JSON explain

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