SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '214ca8ef2c2fc752f605819d8176859d2d24fd6c5e5b981914deb6b077e427ab' 
  AND token = '9o+ggPP0PhSgO6PjweHxljihBADfWMdqgEBhmSa1G8I=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00039

JSON explain

{
  "query_block": {
    "select_id": 1,
    "table": {
      "message": "Impossible WHERE noticed after reading const tables"
    }
  }
}