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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'c2e18280fae013a16175d20c87da7951fb72f845978014d12c66019613580a04' 
  AND token = 'EPhDX9YkckBa2lWmz8+dsQV3ReBTcRWh7Qc0Kemp8WI=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00015

JSON explain

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