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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'dbf879ca8ee5d5c4be2ff3dbeb2f712184f806c1c603db92c4c9f7d517dc857b' 
  AND token = 'Ywxhzh8OCgzWzEOcTDYNvReHT8UYkwFGOdyFpbTRe/o=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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