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SELECT 
  1 
FROM 
  cscart_multi_declock_keys 
WHERE 
  key_id = 'a731bfe1346ba9283b3347bc5a09753727a5c0401e9de5e6faad2c5b9090ad02' 
  AND token = 'vdrOu8aDJUmvs8W7SRuT4rLulAZ+QqafenVhytPCMDQ=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00038

JSON explain

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