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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '4ac3b44ddb5fffa208f16dc3ea61e29a45bc77c254d8b75a07fcde843e9b44e3' 
  AND token = 'BGbxTFVfR4VD9yHowMHwOnhsLrPFqlplt9msEQ6ujpc=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00018

JSON explain

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