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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '16a50a2ed132eeaab063d3eae172707d0b0c1809c187bd5b6e31d5b1ec327d00' 
  AND token = 'hRvIi+ZJfBvMzGOl+fzhL613aLkMVqs5mWeAGL6nd5A=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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