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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'b2733189f6e4fffb6f3396f82113030ccf23d33c6ec0b5e5f965a9243879fe49' 
  AND token = 'v+UPtL6vfXEdAdPGFhz2q4OR4mpLh2Gz/0s6bPvmULM=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00021

JSON explain

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