SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '7e50c20005c9ac1754e96688c7a4968adeb7bdc1617f97ea570ed04db877b6ea' 
  AND token = 'I7ZBZRp2aXROlmm8vfu0Ao2gvy3RJKG42bG25mvlpcc=' 
  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"
    }
  }
}