SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'cb18bbc6691abe8599a4b4d544b2d54fa0ba0bcda5f6fd9ca0b156db9bd99d3b' 
  AND token = '5e3MaKXhv4Ib46zVW9ehKSxdMTq4xxaQHS1hsO21eV0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00042

JSON explain

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