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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'a6b1937512a6521668191abb0541aeef821453a6666798c6df7b7cc26cae489a' 
  AND token = 'mJbRXDqdKsEFWJW4iESRkb5xOoKOXBCvGgoq263wpBw=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00032

JSON explain

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