SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '6b762c8b14e5724d3c6380cefb42372b7cab796b5679cf905aa2033a3d7f208f' 
  AND token = 'rGn38YwTddB9NWSBmN3IWMLOdsVnb00prRpQX+cNe44=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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