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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '8d61620849ad7a36e6a72f3cd5371a8c19ff4cbda67e3ef64a5b483edd623e9c' 
  AND token = 'NCf4Ek5P/aJSqZirwT2dN0bcaF+TmN5Ph37+ZVssU4Q=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00023

JSON explain

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