SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7d435c359235728fbf90efcc3fcc26b3a8928f46adc50851bc19504448f690b8' 
  AND token = 'Z61LPGVHF+6bpPovpNE5Bon8WawSc7aqf/mHpAvGhCE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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