SELECT 
  1 
FROM 
  cscart_june_setuplock_keys 
WHERE 
  key_id = '5f6c4b3623ffe1617726e78ac68ec0d3b61b13fffbdd45b6af7ce9374a24c867' 
  AND token = 'mtc+tR94ZgbbSNr4Vwsy5duK8nFKNKI2AwhLUTzMKc4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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