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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '21f57e3b71d1b4435a1a6303f43b52e033fae340268fd7121ef5a86df33de947' 
  AND token = 'lVTeqilrsln3T/HwjTTeartnx90/vcrTsobDZ+/yluc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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