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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '256eaaeddf0468e83b1130bcdc040376eb4ac769c4a1575622860c5a67bd14ce' 
  AND token = 'fjzwBk/Qy0G3tD2cbUfoUMa++01t7Dmwb7c82zcaBnk=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00035

JSON explain

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