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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6d9fa4c73d33b122159a88ad282d212bd11beaba1e83068d968663644f7a9bb0' 
  AND token = 'ZmvjmaX6Ht6pvcOL8UZrcRjajx0lMpMXEIud3zB+7Hw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00044

JSON explain

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