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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'f51e0442b4406655afcb961e6675ca868cad9d15d0e169f2b84ad1dfa30f3e85' 
  AND token = 'bDIb3ewZ7BmWpo/WctAlYU03UCP113WpNe1hdpeEQA0=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00019

JSON explain

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