SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '993b89b876e4f6de523b7218f848f028ac8ae082357645f3fa358a5415c68cc9' 
  AND token = 'giAEDDC2+dz2qeuVn5vDURvjrc7LO4+hWgB3n1V74YA=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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