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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = '3e9b4b5aa0be13d0065600f8e3561ad69ef84578ecac4367b0e0fa5c2a297b24' 
  AND token = '4MRRVkDLF+5Mcqsq9mQk/jdXWkN3kR7jx9x3UpSXDG0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00025

JSON explain

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