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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'de28c3bc83182de7efe05a2477ff49856cf13f2ccf7212e0650d6539cb09c8fc' 
  AND token = 'RLRFqV71xOEF8Km8Dsz+Rn/Q/0Xo+dUPAMqy3Cq+57M=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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