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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fe08cfed3171d9787ed49b4cf54125a065c376ec4aaffe18755842d186ef1b37' 
  AND token = 'yJ6ErsXAcy/lJtt+Fbb5Nb5aoKXc76Vtf2XfZ10T/C8=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00028

JSON explain

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