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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'd6972a93e81d07829ec57ed6568f7b04d5bb9bdd0a89046b709c301391c50978' 
  AND token = 'gjeGha3I+Rab75WTm809pef0HmiGXAMraMo9qHENefM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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