SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '53fb90340d2bfd0c68df04f10a376318eb952bdb834310c95bf062582703d638' 
  AND token = 'rejMuwN4EVFQc/GjBdVFwlDndsSAg1g7gjYeYPoaqZ4=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00040

JSON explain

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