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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'e3c898d99fe309b1d113432e4adb2a91c52a7392e9ceddfbe3ff662b9fd2ebef' 
  AND token = '3xxu4PL2fpiTxtm1kyRQyGZ2qUrok5wv6zTaLRmjZrE=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00022

JSON explain

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