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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'e4b04dcdc77db846776b2541ff9e423b6fdfabba8fd8225b9c2ff3553016ef71' 
  AND token = 'b6EkQV/MdnKCd3cErO2qS1+EjvpZ+lfeS9J4GnwcaQ0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00024

JSON explain

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