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SELECT 
  1 
FROM 
  cscart_lock_keys 
WHERE 
  key_id = 'fc48be98b84f15d47dac6c7f6d4ddb385a3a1eb7961a16c7cc163b2a5a0a3c00' 
  AND token = 'JNZntX2uO1UA5iD0mu2ulT0s/erGvvcXAkRAKv3oalg=' 
  AND expiry_at > UNIX_TIMESTAMP(NOW())

Query time 0.00027

JSON explain

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