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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8346f5d0593ae23584995e8229e0b42cc0cf3bba99bd813dbd41d4e695b4c82f' 
  AND token = 'c1mhMUsyjedf8IUQ8OucbHUFQ3RQCACknIdKO7csxXY=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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